He is definitely thinking of tricks with fire as fun in a Loel-like way. There is also something Loel-like about how he wistfully concludes he will not be requesting fire tricks if Ivan does not want fire tricks.
"What if the tricks with fire turn out to actually be made of fire?" counters Ivan.
"They are actually made of fire but quite safe. Your cousin will not request fire tricks if you don't want them. But my brother can probably extract fire tricks from me if he wants them."
It is not good to alarm Ivan. Ivan should not be alarmed. Ivan is precious and must be protected.
Ivan is just fucking delightful, that's all. And huggable. So huggable. Mark would absolutely fucking murder anyone who hurt him.
"He's thinking that you are delightful and huggable and that he would cheerfully murder anyone who hurt you."
"Let's confine the murder to people who are, say, David Galen, and not run around with a plasma arc if I have a nasty breakup, huh?"
There are circumstances under which it would be appropriate to murder an (ex-)girlfriend of Ivan's, but so far Ivan seems to have entirely avoided dating the sort of girl who presents that sort of problem.
"Anyway, I wouldn't be cheerful about it, I would be very upset."
He is cheerful now because he is contemplating Ivan's delightfulness. There is a lot of it.
"That is the sort of distinction I seem to take more exposure to pick up on. I can tell with Aleko or our little brother, but I haven't read you - or for that matter Loel and Sarelle - quite enough. Loel almost, but he thinks so differently from me that there's more to learn about how he works in the first place."
And are they anything like Miles?
...There turns out to be, ensconced in Mark's head, an entire third person on top of the two he already resembles. His name is Miles Vorkosigan and he has a wholly separate existence from Mark's - they are brothers, twins-six-years-apart - and Mark contains a nearly perfect copy of his personality for reasons which are not presently clear. It unfolds out of nowhere when he consults it for Kiri's inspection, and the flavour of the simulated Miles-thoughts is completely different from Mark's.
"These people, and two other people and I, are the primes - a political and magical position - in our country. None of them look much like you and Miles - you are very complicated in there - and he doesn't have nearly as much mental resemblance to anybody I've read as you do, based on your model anyway. Sarelle does have an identical twin, but they were born conventionally and are both girls and I'm not much acquainted with Sarelle's sister to comment on her for you."
"My model is perfect," says Mark. His internal representation of Miles agrees, and so does an actual memory of the actual Miles, and so does the evidence of the way they tend to argue about books, with Miles never once complaining that Mark guessed wrong when he interrupted Miles three words into a ten-word sentence to respond as though he'd said the whole thing.
"The balance of evidence available says so, anyway. Do you believe I can read your mind now or shall I go on commenting?"
Miles agrees! If Miles were here he would be highly conflicted on a number of levels about whether or not to let Kiri read him.
"It is very strange that you have a copy of your brother living in your head."
"Maybe we'd better get away from the door in case somebody comes in," says Aleko. They do, avoiding Ivan's radius as they head for the chairs at the bar.
He lags back out of range to limit the amount of childhood trauma Kiri is exposed to, but there is a definite impression of being forced under torture to develop this talent.
Kiri winces. "Well, you got very good at it. Aleko's got what I'd call an excellent model of me he can run which he uses as a conscience, but Miniature Pocket Kiri is not quite so - full."
He is not entirely clear on what a conscience is, but when he checks, Miles certainly believes that Miles has one. Mark compares. No, he does not own such a device himself. There is not such a thing as a coherent internal standard to which he compares his actions to see if they are acceptable.
"Works pretty well for me. Kiri'll be on my case if I do things she doesn't approve of anyway, so might as well consult her in the first place."
"This is a way in which you resemble Loel," Kiri tells Mark. "It's just getting more and more uncanny. At times it's just like you're thinking Loel's thoughts in Sarelle's accent or Sarelle's thoughts with Loel flavoring or something."